While I tried to push the string to open the blind a little the whole 20 pound piece fell off the wall and hit me in the head from 7 feet above. I haven't gotten a severe concussion yet (it happened tonight) but there are symptoms of mild concussion. Also the accident caused an open wound on my scalp. Is there a way to bring guilty people to responsibility?
First off, a deficiency like this isn't about "who is guilty." Nobody is "guilty." Nobody put that 20-lb window blind up there thinking "what fun it will be when somebody gets whacked by this booby-trapped fixture!"
I'm going to make a couple assumptions, which I'll rely on for my answer. First assumption: you're in an apartment complex, with a manager and maintenance dept. Second: they have insurance. Third: there is an indemnity clause in your lease that states that you accepted the residence "as is" pursuant to a move-in inspection. Fourth: you're not actually looking to make a "payday" out of this.
Given those assumptions, we'd move on to actions. First, go to the ER or urgent care facility closest to you and get treatment.
Second, write a letter to the landlord/manager/agent/association, that due to a "hidden hazard" in the rental unit, you sustained an injury that required medical treatment. Detail the nature of the injury and the nature of the hidden deficiency. (i.e. "I proceded to operate the closure for the blinds, and they fell on my head").
Third, give the landlord/manager/agent/association opportunity to respond. Likely, they have insurance that will cover this. Chances are, they will send around a guy to check it out, an Insurance Adjuster will show up to ask you a few questions, and they'll cut you a check to cover your medical bill, and perhaps any lost wages or other costs (cleaning up broken glass? carpet stained with blood, etc.) you incurred.
Fourth, if they fail to respond in a satisfactory manner, you can bring the case to small claims court, and charge them with negligence. Expect to be able to document everything, including photos of the fallen unit that show what was wrong with it, that show that some repair/installation was done that DID NOT COMPLY TO LOCAL CODES. If it was code-compliant, it's very unlikely that you will persuade the court...unless your landlord/agent/association fails to show up.